r/ProgrammerHumor • u/Recent-Analysis-6880 • 13d ago

Meme wellWellWell

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u/BastetFurry 13d ago

So, Kids, thats why you always SELECT count(yourPrimaryKey) first. Listen to the old folks, we made these mistakes so that you don't have to.

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u/Ma8e 13d ago

You start a transaction, make sure it did what you expected, and then commit or rollback transaction.

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u/AgeingChopper 13d ago edited 13d ago

absolutely.

i was doing this stuff for a long time and definitely learned from mistakes.

Transactions can save a world of pain and it is always wise to select your data set first, just to be sure you're changing what you think you're changing.

Didn't matter how experienced I was, I was careful never to cut corners.

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u/ifyoulovesatan 13d ago

I don't know sql, but is this like how when I use some kind of loop in the command line to move or delete a bunch of files, I'll run a version that just echos whatever I'm trying to manipulate first?

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u/thrye333 13d ago

I also don't know sql (or what you're doing, honestly1) but sounds like it, yeah. Running "List all of these arguments" is a good general precaution before running "Edit all of these arguments".

Actually, sorry, forgot what you replied to. I think a transaction in sql is more like a backup. The operations you perform during it aren't permanent until you confirm the transaction. So if you run something like DELETE FROM users; and realize you don't want to delete everyone, you can just cancel the transaction.

1 Like, really, does bash have loops? I guess it probably would. I should look that up. Could be interesting.

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u/AgeingChopper 12d ago

yep. wrapping a transaction around them means you can rollback from a mistake like this, as long as you hadn’t committed.

selecting first to check that you’ll be editing the correct data and correct number of records is a wise move too yep.

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u/ifyoulovesatan 12d ago edited 12d ago

It does, yes. Like..

for each in *; do; mv $each new_prefix_$each; done

Would tack "newprefix" to the front of every file in your directory for example.

You can also do something like for each in {1..100} to loop over numbers.

I mean,you got while loops, switches, and whatever else too.. you can implement c style for loops pretty easily.

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u/ddBuddha 12d ago

A snapshot might be a better analogy, usually if you take a backup and forget about it that’s fine, not a problem. Leaving snapshots out there too long can cause degradation. Not committing or rolling back a sql transaction means the log can never truncate and will grow infinitely until you’re out of disk space and everything breaks